Abstract: To explore the feasibility and accuracy of realtime threedimensional echocardiography (RT3DE) in evaluation of the left ventricular systolic function and synchrony in patients with myocardial infarction. MethodsTwodimensional echocardiography (2DE) or RT3DE was performed on 18 patients with myocardial infarction (the myocardial infarction group) and 16 normal people (the control group). Left ventricular ejection fraction (LVEF), left ventricular enddiastolic volume (LVEDV), left ventricular endsystolic volume (LVESV), the difference(Dif) and standard deviation(SD) of the time to the point with minimal systolic volume(Tmsv) in 16,12, and 6 segments were determined and adjusted by RR interval (TmsvSD% and TmsvDif％) using realtime threedimensional echocardiography and QLAB software. LVEDV, LVESV, and LVEF were obtained by 2DE. ResultsCompared with the control group, LVEF of the myocardial infarction group was decreased(P＜0.05), while TmsvSD% and TmsvDif％ were increased(P＜0.05). LVEDV and LVESV obtained by RT3DE were higher than those obtained by 2DE(P＜0.05), while LVEF by RT3DE was lower than that by 2DE（P＜0.05）. ConclusionRT3DE can objectively evaluate the left ventricular systolic function